Current mode transmitter capable of canceling channel charge error

Abstract

A current mode transmitter includes a first sink current path, through which a current flows from an output port according to a first bias voltage, a charge error canceller, which supplies a current from a high power supply voltage to a current control port in response to an input signal and counteracts a variation of a second bias voltage in response to an inverted input signal, which has an opposite polarity to that of the input signal, and the second bias voltage, and a second sink current path, which sinks current supplied from the output port in response to the second bias voltage and the inverted input signal, the second sink current path being controlled by the current control port. The input signal and the inverted input signal are complementary.

1. A current mode transmitter, comprising:
 a first sink current path, through which a current flows from an output port in accordance with a first bias voltage; 
 a charge error canceller, which supplies a current from a high power supply voltage to a current control port in response to an input signal, and counteracts a variation of a second bias voltage in response to an inverted input signal, which has an opposite phase to that of the input signal, and the second bias voltage; and 
 a second sink current path, which sinks current supplied from the output port in response to the second bias voltage and the inverted input signal, the second sink current path being controlled by the current control port, 
 wherein the input signal and the inverted input signal are complementary. 
 
   
   
     2. The current mode transmitter as claimed in  claim 1 , wherein the second sink current path comprises:
 a first MOS transistor, which has a first port connected to the output port, a second port connected to the current control port, and a gate to which the second bias voltage is applied; and 
 a second MOS transistor, which has a first port that is commonly connected to the second port of the first MOS transistor and the current control terminal, a second port connected to a low power supply voltage, and a gate to which the inverted input signal is applied. 
 
   
   
     3. The current mode transmitter as claimed in  claim 2 , wherein the charge error canceller comprises:
 a current gradient improving circuit, which changes a current gradient of a node connected to the first and second MOS transistors; and 
 a charge counteracter, which counteracts charge errors at the node connected to the first and second MOS transistors. 
 
   
   
     4. The current mode transmitter as claimed in  claim 3 , wherein the current gradient improving circuit comprises a third MOS transistor, which has a first port connected to the high power supply voltage, a second port connected to the current control port, and a gate to which the input signal is applied. 
   
   
     5. The current mode transmitter as claimed in  claim 3 , wherein the charge counteracter comprises:
 a fourth MOS transistor, which has a drain and a source connected to each other, and a gate to which the second bias voltage is applied; 
 a fifth MOS transistor, which has a first port connected to the high power supply voltage, a second port that is connected to the drain and source of the fourth MOS transistor, and a gate to which the inverted input signal is applied; and 
 a sixth MOS transistor, which has a first port that is commonly connected to the drain and source of the fourth MOS transistor and the second port of the fifth MOS transistor, a second port connected to the low power supply voltage, and a gate to which the input signal is applied. 
 
   
   
     6. The current mode transmitter as claimed in  claim 5 , wherein the current gradient improving circuit comprises a third MOS transistor, which has a first port connected to the high power supply voltage, a second port connected to the current control port, and a gate to which the input signal is applied. 
   
   
     7. A current mode transmitter, comprising:
 a first sink current path, through which a current flows from an output port in accordance with a first bias voltage; 
 a second sink current path, which sinks current supplied from the output port in response to a second bias voltage and an inverted input signal, which has an opposite phase to that of an input signal; and 
 means for canceling charge error, including
 means for controlling the second sink current path in accordance with the input signal, and 
 means for counteracting a variation of the second bias voltage in accordance with the inverted input signal, 
 
 wherein the input signal and the inverted input signal are complementary. 
 
   
   
     8. The current mode transmitter as claimed in  claim 7 , wherein the means for canceling charge error comprises:
 first and second transistors connected in series; 
 means for changing a current gradient of a node connected to the first and second transistors; and 
 means for counteracting charge errors at the node connected to the first and second MOS transistors.